1. Field of the Invention
The invention relates to a catheter for medical use which is devised to be introduced into the body of an person for endoscopy, for the injection of a diagnostic liquid, or for a therapeutic purpose. The catheter includes a main tube having a distal end and a proximal end, and is provided with means for connection to external apparatus.
The invention has application in the medical field, and more particularly concerns the specialized manufacturing industry in the design of implements intended, specifically, for use in this area.
2. Discussion of Background and Relevant Material
Catheters are apparatus used more and more for performing, by percutaneous means, either particular treatments of certain organs, or simply for exploring the latter.
One of the illnesses helped by catheters is, for example, arthritis. This illness consists of, in fact, a narrowing of the blood vessels of atheromatis origin resulting in either a partial obstruction, by a stenosis, or a complete obstruction, with thrombosis resulting from this state.
In a number of cases of arthritis, the arterial de-obstruction is carried out by percutaneous means by way of a balloon catheter to force the stenosis to open.
Elsewhere, angiography, which is a radiography of the blood vessels, frequently needs the use of catheters to inject into the veins or arteries of a given region, an opaque substance to view the vessels by means of X-rays.
In all instances of its use, the catheter consists of a main tube provided with a distal and having a shape according to the cavities to be reached. This main tube also comprises a proximal end provided with means for permitting connection of the catheter to external apparatus, such as a valve or an intermediate or other coupling means.
More precisely, these means for connection comprise a cylindrical body have a central bore matching the external diameter of the main tube of the catheter to thereby allow engagement with the proximal end of the latter.
The cylindrical body is made integral with the main tube, by moulding by adhering, or by a solvent method. It is also lengthened at its free end by a cylindrical coupling of universal type.
Thus, the coupling connection is of cylindrical shape and comprises a coaxial pipe having a slight conicity at its inner end, reducing along its section. This pipe is situated in the bore of the main tube of the catheter, and is made to receive, quite precisely, the collar of the matching joint associated with the external apparatus. The coupling additionally comprises at its free end and on its external periphery, notches used to cooperate with a thread present with the matching joint means.
As seen from the above description of a catheter according to the prior state of the art, it is seen that once joined to an apparatus or external tube, the mobility of this catheter is strictly dependent on the mobility of the external apparatus.
Now, it is quite clear that in the course of its progress in the body of the patient, it must be possible to easily orient the distal end of the catheter in such a way as to reach the organ with which it is required to investigate or treat. This orientation only capable of being achieved while imparting an axial displacement or a rotation of the external part of the catheter. To that end, it should be noted that the main tube is generally made rigid, either because of the presence of a wire mandrel introduced into the interior opening, or by means of a braided structure embedded into the thickness of the main tube.
However, in the case where the external apparatus or the tube connected to the catheter are relatively cumbersome, there is inevitably, a limited maneuverability and, in all cases, not very convenient. Besides, depending on the rotation given to the catheter, a smaller resistance even with the apparatus or the tube accompanying its movement could effect a disconnection in any area of the system and, lastly, alter the operation or measurement in progress.
With this object, it is known to conceive the joints, such as taught in the document US-A-4254773, to allow the rotation of the tubes or the elements which are joined one to another. Also, in inserting such a rotary joint between means for connecting the catheter and the tube or the external apparatus, the operator is instigating the rotation of the catheter without imparting to this apparatus or this external tube any identical movement.
However, there are disadvantages associated with these joint means, which include a supplementary element of which it is necessary to keep a supply and store at the medical establishment. Besides, it contributes to additional expenses.
Additionally, this rotary joint introduces the disadvantage that it does not provide any solution to the possible disconnections as described above, but whichever part is manipulated by the operator, i.e. the rotary joint or the catheter, the movement is transmitted less through the connection, thus separating the catheter and the rotary joint. In addition, it should be noted that the proximity of the latter and the means for coupling the catheter may lead the operator to making an incorrect movement, and inevitably, provoke a disconnection.